The present invention relates to a deflection yoke device for use in a color cathode ray tube of a television receiver, a computer display or the like.
Generally, convergence properties are affected by a shift of a central axis of a deflection yoke device from a central axis of a color cathode ray tube or a so-called deflection yoke tilt such that the central axes cross each other at a certain angle. As a solution to this, the following technique has been disclosed in JP 11 (1999)-54067 A.
As shown in FIG. 8, a deflection yoke device 1 is provided with a deflection yoke 3 having a configuration in which horizontal and vertical deflection coils 2 for detecting electron beams emitted from an electron gun of a color cathode ray tube in a horizontal direction and in a vertical direction, respectively, are positioned on an insulation frame 21. A pair of U-shaped cores 4a and 4b are positioned on the electron gun side of the deflection yoke 3 so as to be opposed to each other with a path of the electron beams interposed therebetween, and quadrupole coma correcting coils 5a and 5b are wound around the U-shaped cores 4a and 4b, respectively. The U-shaped cores 4a and 4b are slidable in a vertical direction or in a lateral direction by a sliding mechanism (not shown).
According to this configuration, when a central axis shift in a vertical direction between the color cathode ray tube and the deflection yoke 3 causes a YH misconvergence as shown in FIG. 9A, the pair of U-shaped cores 4a and 4b provided with the coma correcting coils 5a and 5b are slid in a vertical direction as shown by an arrow in FIG. 10A. This allows the YH misconvergence due to the central axis shift between the color cathode ray tube and the deflection yoke 3 to be corrected without tilting the deflection yoke 3. Further, when a central axis shift in a lateral direction between the color cathode ray tube and the deflection yoke 3 causes a YV misconvergence as shown in FIG. 9B, the pair of U-shaped cores 4a and 4b provided with the coma correcting coils 5a and 5b are slid in a horizontal direction as shown by an arrow in FIG. 10B. This allows the YV misconvergence due to the central axis shift between the color cathode ray tube and the deflection yoke 3 to be corrected without tilting the deflection yoke 3.
However, in order to correct the misconvergence, the above-mentioned configuration requires a space or sliding mechanisms for allowing the U-shaped cores 4a and 4b to be slidable in a vertical direction or in a lateral direction from positions shown by solid lines to positions shown by dashed lines as shown in FIGS. 10A and 10B. Consequently, there is a possibility that a distance from the electron beams to each end of the U-shaped cores 4a and 4b might increase undesirably, which causes a reduction of sensitivity (efficiency) of the coma correcting coils 5a and 5b. Further, it is necessary to employ a mechanical component for allowing the U-shaped cores 4a and 4b to be slidable, which results in a complicated configuration.
Therefore, with the foregoing in mind, it is an object of the present invention to provide a deflection yoke device that can correct a misconvergence with a simplified configuration without reducing a sensitivity of coma correcting coils.
The deflection yoke device of the present invention includes: a deflection yoke for deflecting electron beams in a horizontal direction and in a vertical direction, the electron beams being emitted from an electron gun of a color cathode ray tube; coma correcting coils positioned on an electron gun side of the deflection yoke so as to be opposed to each other in such a manner that the electron beams pass therebetween; and a pair of cores around which the coma correcting coils are wound. In the deflection yoke device, a sliding mechanism further is provided for sliding each of the coma correcting coils with respect to the corresponding core.
According to the above-mentioned configuration, ends of the cores can be positioned in contact with or in close proximity to a neck portion of the color cathode ray tube, thereby preventing a reduction of sensitivity of the coma correcting coils. Further, it is required for the configuration only to make the coma correcting coils slidable with respect to the cores, which eliminates the need for an additional mechanical component for sliding the cores as in the prior art.